sched: Use proper conditional flags to fix 32 bit compile failures

Fix 32-bit compilation issues by using proper conditional checks
for preempt and irqsoff trace event threshold variables.

Change-Id: I2b67cf6c33890e5373e69091c4812bec9302dee5
Signed-off-by: Lingutla Chandrasekhar <clingutla@codeaurora.org>